This review concluded that stannous fluoride dentifrices reduce gingivitis and plaque formation in comparison with conventional dentifrices, but that differences in outcome measures make it difficult to assess the magnitude of the effect. However, given the variability of the studies and limitations in the review methods, the reviewers' conclusions may not be reliable.

Authors' objectives

To evaluate the effects of stannous fluoride (SnF2) on gingivitis.

Searching

MEDLINE and the Cochrane CENTRAL Register were searched up to August 2005; the search terms were reported. Only publications in the English language were eligible for inclusion.

Study selection

Study designs of evaluations included in the review

Randomised controlled trials (RCTs) and controlled trials of at least 6 months' duration that reported baseline and follow-up data were eligible for inclusion in the review.

Specific interventions included in the review

Studies evaluating formulations of tin combined with fluoride were eligible for inclusion. Studies where patients had recently received systemic medications, including antibiotics and non-steroidal anti-inflammatory drugs, within the last 6 months were excluded. The included studies compared dentifrice or gel, mouth rinse, or combined dentifrice and mouth rinse containing SnF2 with dentrifices containing sodium fluoride (NaF) or sodium monofluorophosphate, or placebo. In the majority of the included studies the products were used by participants at home without supervision.

Participants included in the review

Studies of participants without periodontitis or systemic disorders were eligible. The included studies were mainly of healthy adults; some studies included adolescents and one included schoolchildren.

Outcomes assessed in the review

The primary outcome measure was gingivitis. The review also assessed the degree of plaque formation and staining. The included studies used different outcome measures (e.g. gingival index or Turesky index).

How were decisions on the relevance of primary studies made?

Two reviewers independently screened the papers and any disagreements were resolved through discussion.

Assessment of study quality

The reviewers assessed the method of randomisation, allocation concealment, blinding of the examiners and the completeness of follow-up. The authors did not state how the validity assessment was performed.

Data extraction

The authors did not state how the data were extracted for the review, or how many reviewers performed the data extraction. Means and standard deviations were extracted or, where appropriate, calculated by the reviewers.

Methods of synthesis

How were the studies combined?

The studies were pooled and the weighted mean difference (WMD) and 95% confidence interval (CI) calculated using a random-effects model.

How were differences between studies investigated?

Heterogeneity was assessed using the I-squared statistic; differences between the studies were also discussed in the text of the review.

Results of the review

Fifteen studies (n=4,989) were included in the review, of which 14 were RCTs (n=4,924).

The method of randomisation was unclear in several studies, as was the issue of allocation concealment in all but 4 studies. All but 2 (single-blind) studies were double-blind. Three studies stated the reasons for drop-outs and in 3 studies the number of drop-outs exceeded 10%.

Studies assessing gingivitis used several different outcome measures and showed diverse results. Six studies of SnF2 dentifrices were pooled; these showed a statistically significant reduction in gingivitis compared with control (gingival index WMD -0.15, 95% CI: -0.20, -0.11; I-squared 91.1%). Two studies of SnF2 dentifrices also showed a statistically significant reduction in the severity of gingivitis (gingivitis severity index WMD -0.21, 95% CI: -0.27, -0.14; I-squared 80.1%). However, there was evidence of significant statistical heterogeneity in both pooled results.

Studies on plaque used several different outcome measures and reported diverse results. Four studies that assessed plaque formation using the Turesky index were pooled and showed a significant difference in favour of SnF2 dentifrices or gel in comparison with control (WMD -0.31, 95% CI: -0.54, -0.07; I-squared 91.7%). However, there was evidence of significant statistical heterogeneity and no differences were found when studies assessing the plaque index were pooled. The majority of studies showed a statistically significant increase in staining with different SnF2 formulations in comparison with NaF. There was insufficient data to perform a meta-analysis of SnF2 mouth rinse and combinations of dentifrice and mouth rinse.

Authors' conclusions

Compared with conventional dentifrices, the use of SnF2 results in reductions in gingivitis and plaque; the magnitude of the effect is difficult to assess due to heterogeneity in the study outcome measures.

CRD commentary

The review stated a clear question and inclusion criteria. The search was limited so it is possible that relevant studies were missed. The reviewers made little apparent effort to search specifically for unpublished studies and, as only English language studies were eligible, it is possible that language and publication bias may have been introduced into the review, as the authors acknowledged. The authors reported methods to reduce errors and bias when selecting the studies, but it is unclear whether similar approaches were used for the data extraction and quality assessment processes. The results of the individual studies appeared diverse overall and only a few studies indicated a statistically significant benefit of SnF2. Only a small selection of the identified studies was included in the pooled analysis; the pooled selection may not be a good representation of the existing evidence base. In view of these limitations, and as the authors themselves advised, the conclusions should be interpreted with caution.

Implications of the review for practice and research

The authors did not state any specific implications for practice or further research.

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.